Suction device provided with negative pressure regulating mechanism

ABSTRACT

The invention comprises a suction housing connected to a negative pressure forming means to suck in fluids, a suction opening member mounted on the suction housing, a part of which is caused to contact the surface of an object, and which defines a pressure-reduced area together with the suction housing and the surface of an object, and a means for maintaining the distance between the suction housing and the surface of an object at a predetermined distance, wherein the suction opening member and the surface of an object where in contact with each other are caused to be detached from each other partially or entirely due to the increase in the fluid pressure difference between the inside and the outside of the pressure-reduced area, resulting in the communication between the inside and the outside of the pressure-reduced area, allowing the outside fluid to flow into the pressure-reduced area.

TECHNICAL FIELD

This invention relates to a device adhering or attempting to adhere tothe surface of an object when negative pressure is formed internally,and having a mechanism which adjusts such negative pressure by taking inan ambient fluid such as air or water.

The present invention also relates to a device adhering to the surfaceof an object when negative pressure is formed internally and movingalong such surface, and having a mechanism which adjusts such negativepressure by taking in an ambient fluid such as air or water.

The present invention further relates to a device sucking in materialswhich exist on the surface of an object when negative pressure is formedinternally, and having a mechanism which adjusts such negative pressureby taking in an ambient fluid such as air or water.

PRIOR ART

An example of those devices that adhere or attempt to adhere to surfaceswhen negative pressure is formed internally or those devices that adhereto and move along surfaces when negative pressure is formed internallyincludes the one described below:

A device capable of adhering to and moving along various inclined orsubstantially vertical surfaces of ships, buildings, etc. was disclosedin patent application Ser. No. 60-26752 (U.S. Pat. No. 4,095,378 Claimsand Drawings).

The device comprises a suction housing; a plurality of wheels secured tosuch suction housing as a means for mobility; a suction opening memberconnected to such suction housing having a free end which is caused tocontact the surface of an object; a negative pressure forming means todischarge externally the fluid contained in a pressure-reduced areadefined by said suction housing, said surface and said suction openingmember; and a relief valve which maintains vacuum pressure at a constantlevel, generally called a vacuum breaker, to maintain the value of suchnegative pressure at a predetermined level by allowing an ambient fluidto flow into such pressure-reduced area if and when the negativepressure inside such pressure-reduced area exceeds such predeterminedlevel.

In such a device, the energization of the negative pressure formingmeans causes the fluid inside the pressure-reduced area to be dischargedexternally, and the pressure of the fluid which acts on the suctionhousing due to the fluid pressure difference between the inside and theoutside of the pressure-reduced area is caused to be transmitted to thesurface of an object via the wheels, such fluid pressure allowing thedevice to adhere to the surface. Additionally, the rotation of thewheels by way of a driving means, such as an electric motor, during suchadhesion state allows the device to move along the surface due to theaction of such wheels.

Further, such a device has a remote-controlled working device, such as ameans for blasting abrasives against the surface inside thepressure-reduced area mounted thereon, so as to allow various operationson the surface of an object in a safe and efficient manner.

A more detailed explanation of the purpose of the vacuum breaker on theaforesaid device follows. If the negative pressure inside thepressure-reduced area exceeds a predetermined value, the adhesive powerof said device to the surface of an object becomes excessive, causingdestruction due to a lack of mechanical strength thereof. If thenegative pressure inside said pressure-reduced area exceeds apredetermined value, the negative pressure of the negative pressureforming means will also increase, and, characteristically of saidnegative pressure forming means, the increase in negative pressurenecessarily decreases the amount of the fluid sucked in, resulting inthe decrease in the amount of the fluid reaching said negative pressureforming means from said pressure-reduced area. In case of such a devicehaving a means for blasting abrasives against the surface of an objectmounted thereon, the abrasives after being blasted issuction-transported by the flow of the fluid reaching the negativepressure forming means from the pressure-reduced area, and the abrasivesis separated and collected by a powder and granular material separatingmeans installed at the upstream side of the negative pressure formingmeans. In such a device, if the amount of the fluid decreases, theamount of abrasives which can be suction-transported decreasescorrespondingly, resulting in lowered performance efficiency of suchdevice.

As understandable from the above explanation, the purpose of a vacuumbreaker on such a device is to prevent the destruction of the devicecaused by excessive negative pressure and to prevent the decrease in theamount of the fluid which flows to the negative pressure forming meansfrom the pressure-reduced area.

The above-described conventional device has the following problems to besolved.

With respect to the traditional device, a vacuum breaker is installed onthe suction housing and, if and when the negative pressure inside thepressure-reduced area exceeds a predetermined level, the ambient fluidflows into the pressure-reduced area through the vacuum breaker tomaintain the negative pressure at the predetermined level. However, theflow of the fluid which flows from the vacuum breaker and reaches thenegative pressure forming means via the interior of the suction housingis not necessarily an effective flow of the fluid to effectivelysuction-transport powder and granular materials, such as abrasives,existing on the surface; As easily understood in case of such surface ofan object being a floor surface, the flow of the fluid which flows fromthe vacuum breaker and reaches the negative pressure forming means viathe interior of the suction housing does not contribute much to thesuction-transportation of powder and granular materials, such asabrasives, existing on the surface. Effective suction-transportation ofpowder and granular materials, such as abrasives, existing on thesurface of an object requires that the fluid actually flows through thelocation of such material and moves such material with wind pressure.

Additionally, in case of the surface of an object made of extremelysmooth material, such as sheet glass, a suction opening member made ofnon-air-permeable material, such as rubber, will adhere to the surfacegap-free, causing the entire flow of the fluid which flows from outsidethe suction device to the negative pressure forming means through theinterior of such suction device to flow from a vacuum breaker. In such acase, no material clinging to the surface outside the pressure-reducedarea and desired to be suction-transported is allowed to besuction-transported nor is it allowed to enter the inside of thepressure-reduced area, even if such material is in a powder form. Anexception is when the suction opening member is made of air permeablematerial, such as a brush. It is extremely difficult, however, to have abrush to be equipped with a negative pressure adjustment function, suchas that of a vacuum breaker.

Additionally required of the traditional device is the use of a largevacuum breaker when the fluid sucking capacity of a negative pressureforming means is considerably great. The reason is as follows. In orderto prevent the negative pressure in the pressure-reduced area frombecoming excessive, the amount of the fluid which flows through a vacuumbreaker needs to be increased. In order to achieve this, needed is alarge vacuum breaker having a large passage valve. A large vacuumbreaker necessarily makes a device larger and causes the manufacturingcost thereof to increase.

Accordingly, it is a primary technical objective of this invention toprovide a suction device capable of causing the entire flow of a fluidwhich flows from outside the suction device, through the interiorthereof and to a negative pressure forming means to pass extremely closeto the surface of an object, thereby effectively suction-transportingmaterials existing on the surface, whether existing inside or outside apressure-reduced area, and further to provide a suction device whichdoes not require a large vacuum breaker.

Certain problems associated with prior art and attempted to be solved bythe present invention were discussed above with respect to devices whichadhere to or attempt to adhere to surfaces when negative pressure isformed internally or devices which adhere to surfaces and move alongsuch surfaces when negative pressure is formed internally.

Next, problems associated with prior art and attempted to be solved bythe present invention will be discussed below with respect to deviceswhich adhere to or attempt to adhere to surfaces when negative pressureis formed internally or devices which suck in materials which exist onsurfaces when negative pressure is formed internally.

An example of those devices that adhere or attempt to adhere to surfaceswhen negative pressure is formed internally or those devices that suckin materials which exist on surfaces when negative pressure is formedinternally is a suction nozzle used to suck in and collect powder andgranular materials of higher specific gravity, such as abrasives withiron as a raw material, which exist on the surface of an object.Traditionally, in order to suck in and collect abrasives existing on thesurface of an object, a suction nozzle connected via suction hose to anegative pressure forming means is held by an operator and the suctionopening of such suction nozzle is thrust into the abrasives. If a greatquantity of abrasives is sucked in at one time, however, such materialbecomes blocked up inside the suction hose, resulting in a drasticdecrease in the flow of the fluid which flows from outside such suctionnozzle, through the interior of the suction nozzle and the suction hoseand to the pressure reduction forming means, frequently causingdifficulties in the suction and collection of the abrasives.

Accordingly, it is a technical objective of this invention to provide asuction device capable of causing the suction opening member to bedetached, due to the increase in the negative pressure inside thesuction nozzle or the suction device, from the surface of an object, orthe surface of the material to be suction-transported, before suchmaterial to be suction-transported becomes blocked up in the midst ofthe transportation route, in order to stop the excessive flow of thematerial into the suction opening member, thereby allowing effectivesuction-transportation of the material, and further to provide a suctiondevice capable of causing the entire flow of the fluid which flows fromoutside the suction device, through the interior thereof and reaches anegative pressure forming means to pass extremely close to the surfaceof the material to be suction-transported, thereby allowing moreeffective suction-transportation of the material.

SUMMARY OF THE INVENTION

Provided according to the present invention in order to solve thetechnical problems described above is a suction device comprising: asuction housing connected to a negative pressure forming means to suckin a fluid; a suction opening member installed on said suction housing,a part of which is caused to contact the surface of an object, and whichdefines a pressure-reduced area together with said suction housing andsaid surface; and, a means for maintaining the distance between saidsuction housing and said surface at a predetermined distance; saidsuction device having a negative pressure adjusting means whereby thesuction opening member and the surface where in contact with each otherbecome detached from each other partially or entirely due to theincrease in the fluid pressure difference between the inside and theoutside of said pressure-reduced area, resulting in the communication ofthe inside and the outside of said pressure-reduced area, allowing theoutside fluid to flow into said pressure-reduced area.

According to the device of the present invention, the energization ofthe negative pressure forming means causes the fluid inside thepressure-reduced area to be sucked in, resulting in the increase in thenegative pressure of the inside of the pressure-reduced area, and, dueto such increase in the negative pressure, the suction opening memberand the surface where in contact with each other become detached fromeach other partially or entirely, resulting in the communication betweenthe inside and the outside of the pressure-reduced area, allowing theoutside fluid to flow into the pressure-reduced area, stopping theincrease in the negative pressure inside the pressure-reduced area,thereby maintaining the negative pressure at a constant level.

Further according to the device of the present invention, the suctionopening member has the function of a valve, and because thecross-sectional area of the passage as a valve may be enlarged greatly,the suction opening member itself can be said to have a negativepressure adjusting capacity similar to that of a large vacuum breaker.According to the present invention, therefore, devices may be madesmaller and lighter and the manufacturing cost thereof lower, comparedto traditional devices which use large vacuum breakers.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a top view of the first-most preferred embodiment of thedevice configured according to the present invention.

FIG. 2 is a side view of the bottom of the device shown in FIG. 1

FIG. 3 is a sectional view along the line A—A of the device shown inFIG. 1.

FIG. 4 is a sectional view along the line B—B of the device shown inFIG. 1.

FIG. 5 is an enlarged sectional view of the area C of the device shownin FIG. 3.

FIG. 6 is an enlarged sectional view of the area D of the device shownin FIG. 4.

FIG. 7 is a top view of the first embodiment of the suction openingmember of the device shown in FIG. 1, seen from the surface side of anobject.

FIG. 8 is a top view of the groove-forming member to be pasted onto thesuction opening member of FIG. 7.

FIG. 9 is a top view of the second embodiment of the suction openingmember of the device shown in FIG. 1, seen from the surface side of anobject.

FIG. 10 is a top view of the groove-forming member to be pasted onto thesuction opening member of FIG. 9.

FIG. 11 is an enlarged sectional view of the area E of the firstembodiment of the suction opening member shown in FIG. 7.

FIG. 12 is an enlarged sectional view of the area F of the secondembodiment of the suction opening member shown in FIG. 9.

FIG. 13 is a sectional view showing the detached state of the main partof the suction opening member of the device shown in FIG. 4.

FIG. 14 is an enlarged sectional view of the area G of the device shownin FIG. 13.

FIG. 15 shows the border line where the main part of the suction openingmember and the surface of an object begin to detach from each other inthe enlarged sectional view of the area E of the fist embodiment of thesuction opening member shown in FIG. 11.

FIG. 16 shows the border line where the main part of the suction openingmember and the surface of an object begin to detach from each other inthe enlarged sectional view of the area F of the second embodiment ofthe suction opening member shown in FIG. 12.

FIG. 17 is a sectional view of the second-most preferred embodiment ofthe device configured according to the present invention.

FIG. 18 is an enlarged sectional view of the area H of the device shownin FIG. 17.

FIG. 19 is a pneumatic circuit diagram of the device shown in FIG. 17and FIG. 18.

FIG. 20 shows fluid pressure changes of the pressure-reduced area andthe second pressure-reduced area, the energized state of the solenoidvalve and the state of detachment of the main part of the suctionopening member from the surface of an object of the device shown in FIG.17 through FIG. 19.

DETAILED DESCRIPTIONS OF PREFERRED EMBODIMENTS

Preferred embodiments of the device configured according to the presentinvention will be described in detail below, referring to the figuresattached hereto.

In reference to FIG. 1 through FIG. 12, the device illustrated thereinhas the suction housing 2, said suction housing 2, made of a rigidmaterial, made up of a cylinder with one end opened and a ring-shapeddisk welded onto the outer periphery of such opening of the cylinder.

Welded onto one side of the suction housing 2 is the connecting pipe 10a, said connecting pipe 10 a being connected to a negative pressureforming means (not illustrated), such as a vacuum pump, via flexiblesuction hose (not illustrated).

Welded onto the sides of the suction housing 2 are two sets ofinstallation members for electric motors with reduction gears 12, madeof a rigid material.

Mounted on each of the two sets of installation members for electricmotors with reduction gears 12 are the electric motor with a reductiongear 24RR having the driving wheel 22 a on the driving shaft thereof andthe electric motor with a reduction gear 24LL having the driving wheel22 c on the driving shaft thereof, on the one hand, and the electricmotor with a reduction gear 24R having the driving wheel 22 b on thedriving shaft thereof, and the electric motor with a reduction gear 24Lhaving the driving wheel 22 d on the driving shaft thereof, on the otherhand.

Mounted on the outer periphery of the disk of the suction housing 2 isthe bellows 38 of the overall approximate shape of a ring made of arelatively flexible material, such as polyurethane rubber or plastic,using bolts and nuts and utilizing the ring-and-disk-shaped binder madeof a rigid material 39 as a supplementary fastening means. The bellows38 comprises the flanges 381 made on both ends of the bellows 38 and themain part of the bellows 382.

Mounted on the bellows 38 is the outer periphery of the movablepressure-receiving member 37, which is a ring-shaped disk made of arigid material, using a bolt and nuts and utilizing the binder made of arigid material 39, which is a ring-shaped disk, as a supplementaryfastening means.

Welded onto the binder 39 located on the side where the movablepressure-receiving members 37 is located are four guide pins 41, saidfour guide pins each inserted into each of the four holes made on thedisk of the suction housing 2, the flange 381 located on the side wheresaid disk is located, and the binder 39 in a freely slidable manner.Additionally, four compressed coil springs 43 are inserted in the guidepins 41 between the two binders 39. Fixed onto the guide pins 41 withbolts are the end plates 42 which have the function of a stopper.

Mounted at the inner periphery of the movable pressure-receiving member37 is the suction opening member 36, made of a relatively flexiblematerial, such as polyurethane rubber or plastic, with bolts and nuts.The suction opening member 36, which has the overall approximate shapeof a ring-shaped disk, comprises the flange 361, the bellows 362consisting of the upper wall which extends from the flange 361 towardthe surface of an object 1 and toward the inside of the pressure-reducedarea 50 and the lower wall which extends from said upper wall toward thesurface of an object 1 and toward the outside of the pressure-reducedarea 50, the main part 363 which extends from the bellows 362, along thesurface of an object 1 and toward the outside of the pressure-reducedarea 50, and the extension 364 which extends from the main part 363 awayfrom the surface of an object 1 and toward the outside of thepressure-reduced area 50.

The suction opening member 36, together with the suction opening 2, thebellows 38, the movable pressure-receiving member 37 and the surface ofan object 1, defines the pressure-reduced area 50.

Pasted onto the area which faces the surface of an object 1 of the mainpart 363 of the suction opening member 36 is a sheet-shapedgroove-forming member 37 of the shape shown in FIG. 8 or FIG. 10, madeof a material with a low coefficient of friction, such as ultrahighmolecular polyethylene. By way of the groove-forming member 37 beingpasted onto the main part 363, the area which faces the surface of anobject 1 of the main part 363 of the suction opening member 36 is causedto form alternately the groove 371 which communicates with the outsideof the pressure-reduced area 50 and the groove 372 which communicateswith the inside of the pressure-reduced area 50.

The groove 371 which communicates with the outside of thepressure-reduced area 50 has the effect of allowing the fluid outsidethe pressure-reduced area 50 to flow into the pressure-reduced area 50.The groove 372, which is constantly in the state of negative pressure,has the effect of allowing the pressure of the fluid outside thepressure-reduced area 50 to constantly push the main part 363 againstthe surface of an object 1.

In regards to the difference between the groove-forming member 37 shownin FIG. 8 and the groove-forming member 37 shown in FIG. 10, thegroove-forming member 37 shown in FIG. 8 has grooves 371, all of thesame shape whereas the groove-forming member 37 shown in FIG. 10 has twodifferent lengths of grooves arranged alternately.

Additionally, by changing the thickness of the material of the sheet forthe groove-forming member 37, the depth of the grooves may easily bechanged to any desired depth, allowing the selection of a desired depthof the grooves in accordance with the suction capacity of thenegative-pressure forming means.

Furthermore, the groove-forming member 37, when worn down causing thedepth of the grooves to decrease, may be changed to a new groove-formingmember 37, easily restoring the depth of the grooves.

Actions and effects of the device described above will be explainedbelow.

When the electric motors with reduction gears 24L, 24LL, 24R and 24RRare operated to rotate and drive the driving wheels 22 d, 22 c, 22 b and22 a in the same direction, the device will move straight (forward orbackward) along the surface of an object 1. When the driving wheels 22 dand 22 c, on one hand, and the driving wheels 22 b and 22 a, on theother hand, are rotated and driven to opposite directions, the devicewill turn (left or right).

When the negative pressure forming means (not illustrated) is energized,the fluid, such as air, inside the pressure-reduced area 50 becomesdischarged externally through the connecting pipe 10 a and suction hose(not illustrated), resulting in the desired reduction of the pressure ofthe pressure-reduced area 50.

When the pressure is so reduced of the pressure-reduced area 50, thepressure of the ambient fluid, such as air, which acts on the suctionhousing 2 due to the fluid pressure difference between the inside andthe outside of the pressure-reduced area 50, is transmitted to thesurface of an object 1 via the two sets of installation members 12 forthe electric motors with reduction gears, the four sets of electricmotors with reduction gears 24R, 24L, 24RR and 24LL and the four sets ofdriving wheels 22 a, 22 c, 22 b and 22 d, causing the device tosuction-adhere to the surface of an object 1 due to the pressure of theambient fluid.

While the pressure of the inside of the pressure-reduced area 50 ismaintained at a desired level, the main part 363 of the suction openingmember 36 is forced to be in firm contact with the surface of an object1 by the pressure of the outside of the pressure-reduced area 50,thereby stopping as much as possible the fluid outside thepressure-reduced area 50 from flowing internally.

Many grooves are formed in the area of the main part 363 which faces thesurface of an object 1. More specifically, the groove 371 whichcommunicates with the outside of the pressure-reduced area 50 and thegroove 372 which communicates with the inside of the pressure-reducedarea 50 are formed alternately. The groove 372 is constantly in thestate of negative pressure, and therefore, the main part 363 isnecessarily pushed against the surface of an object 1 by the pressure ofthe fluid outside the pressure-reduced area 50.

The movable pressure-receiving member 37 is forced to move away from thesurface of an object 1 by the pressure of the fluid outside thepressure-reduced area 50, but such movement is stopped by the compressedcoil spring 43.

Now, when the negative pressure inside the pressure-reduced area 50increases, the movable pressure-receiving member 37 being under theforce of being moved away from the surface of an object 1 by thepressure of the fluid outside the pressure-reduced area 50 receivesgreater force, resulting in the movable pressure-receiving member 37overcoming the spring force of the compressed coil spring 43 and movingaway from the surface of an object 1. The movable pressure-receivingmember 37 then pulls the bellows 362 of the suction opening member 36away from the surface of an object 1, finally resulting in the area ofthe main part 363 closest to the inside of the pressure-reduced area 50being detached from the surface of an object 1 as is illustrated in FIG.13 and FIG. 14, causing the fluid outside the pressure-reduced area 50to flow into the pressure-reduced area 50 via the groove 371, stoppingthe increase in the negative pressure of the inside of thepressure-reduced area 50. When the pressure of the inside of thepressure-reduced area 50 returns to the desired level, the movablepressure-receiving member 37 moves toward the surface of an object 1 bythe spring force of the compressed coil pressure 43, and the suctionopening member 36 returns to the same state as when the pressure of theinside of the pressure-reduced area 50 was maintained at the desiredlevel.

In FIG. 15, the two-dot chain lines J and K show the borderlines wherethe main part 363 and the surface of an object 1 begin to detach fromeach other. When the border line is J when the main part 363 and thesurface of an object 1 begin to detach from each other, the groove 371is not yet in communication with the inside of the pressure-reduced area50, and the fluid outside the pressure-reduced area 50 does not flowinside the pressure-reduced area 50. When the border line is K when themain part 363 and the surface of an object 1 begin to detach from eachother, the groove 371 is in communication with the inside of thepressure reduced area 50, and the fluid outside the pressure-reducedarea 50 flows inside the pressure-reduced area 50.

In FIG. 16, the two-dot chain lines J and K show the borderlines wherethe main part 363 and the surface of an object 1 begin to detach fromeach other. When the border line is J when the main part 363 and thesurface of an object 1 begin to detach from each other, the longergroove of the grooves of two different lengths is in communication withthe inside of the pressure-reduced area 50, but the shorter groove isnot yet in communication with the inside of the pressure-reduced area50. When the border line is K when the main part 363 and the surface ofan object 1 begin to detach from each other, all the grooves 371 are incommunication with the inside of the pressure-reduced area 50. In otherwords, the amount of the fluid which flows from the outside to theinside of the pressure-reduced area 50 is greater when the border lineis K when the main part 363 and the surface of an object 1 begin todetach from each other than when the border line is J when the main part363 and the surface of an object 1 begin to detach from each other.

In other words, the shapes of the grooves illustrated in FIG. 9, FIG.10, FIG. 12 and FIG. 16 are made in such a way that the size of thepassage of the grooves 371 which connects the outside and the inside ofthe pressure-reduced area 50 is increased as the fluid pressuredifference between the inside and the outside of the pressure-reducedarea 50 increases and that the size of such passage is decreased as suchincrease in the fluid pressure difference is cancelled.

The grooves of the shape illustrated in FIG. 9, FIG. 10, FIG. 12 andFIG. 16 are superior to the grooves of the shape illustrated in FIG. 7,FIG. 8, FIG. 11 and FIG. 15 in the adjusting function of fine tuning thepressure of the pressure-reduced area 50. However, the choice betweenthe grooves of the shape illustrated in FIG. 9, FIG. 10, FIG. 12 andFIG. 16 and the grooves of the shape illustrated in FIG. 7, FIG. 8, FIG.11 and FIG. 15 depends upon the purpose of the utilization of the deviceof the present invention.

The most preferred embodiment of the device configured according to thepresent invention was described above. The second-most preferredembodiment of the device configured according to the present inventionwill be described below by referring to attached figures.

FIG. 17 shows a sectional view of the second-most preferred embodimentof the device configured according to the present invention. A top viewof said second-most preferred embodiment is omitted because it is thesame as the top view of the most preferred embodiment of the deviceconfigured according to the present invention shown in FIG. 1. FIG. 17then is a sectional view along A—A of the second-most preferredembodiment of the device configured according to the present inventionshown in FIG. 1.

In reference to FIG. 17 through FIG. 19, the device illustrated thereinhas the suction housing 2, said suction housing 2, made of a rigidmaterial, made up of a cylinder with one end opened and a ring-shapeddisk welded onto the outer periphery of such opening of the cylinder.

Welded onto one side of the suction housing 2 is the connecting pipe 10a, said connecting pipe 10 a being connected to a negative pressureforming means (not illustrated), such as a vacuum pump, via flexiblesuction hose (not illustrated).

Welded onto the sides of the suction housing 2 are two sets ofinstallation members for electric motors with reduction gears 12, madeof a rigid material.

Mounted on each of the two sets of installation members for electricmotors with reduction gears 12 are the electric motor with a reductiongear 24RR having the driving wheel 22 a on the driving shaft thereof andthe electric motor with a reduction gear 24LL having the driving wheel22 c on the driving shaft thereof, on the one hand, and the electricmotor with a reduction gear 24R having the driving wheel 22 b on thedriving shaft thereof and the electric motor with a reduction gear 24Lhaving the driving wheel 22 d on the driving shaft thereof, on the otherhand.

Mounted on the outer periphery of the disk of the suction housing 2 isthe bellows 38 of the overall approximate shape of a ring made of arelatively flexible material, such as polyurethane rubber or plastic,using bolts and nuts and utilizing the ring-and-disk-shaped binder madeof a rigid material 39 as a supplementary fastening means. The bellows38 comprises the flanges 381 made on both ends of the bellows 38 and themain part of the bellows 382.

Mounted on the bellows 38 is the outer periphery of the movablepressure-receiving member 37, which is a ring-shaped disk made of arigid material, using a bolt and nuts and utilizing the binder made of arigid material 39, which is ring-shaped disk, as a supplementaryfastening means.

Additionally mounted on the disk part of the suction housing 2, closerto the center of the pressure reduced area 50 than where theaforementioned bellows 38 is mounted, is another set of bellows 38having the same sectional shape as the aforementioned bellows 38, usingbolts and nuts and utilizing the ring-and-disk shaped binders 39, madeof a rigid material, as a supplementary fastening means.

As easily understood by FIG. 17, the two sets of bellows 38 areconcentrically shaped.

The two sets of bellows 38 are each mounted on the outer and the innerperipheries of the ring-and-disk shaped movable pressure-receivingmember 37, made of a rigid material, using bolts and nuts and utilizingthe ring-and-disk shaped binders 39, made of a rigid material, as asupplementary fastening means.

The two sets of bellows 38, together with the suction housing 2 and themovable pressure-receiving member 37, define the second pressure-reducedarea 383.

Mounted at the inner periphery of the movable pressure-receiving member37 is the suction opening member 36, made of a relatively flexiblematerial, such as polyurethane rubber or plastic, with bolts and nuts.The suction opening member 36, which has the overall approximate shapeof a ring-shaped disk as is the case with the device shown in FIG. 1through FIG. 16, comprises the flange 361, the bellows 362 consisting ofthe upper wall which extends from the flange 361 toward the surface ofan object 1 and toward the inside of the pressure-reduced area 50 andthe lower wall which extends from said upper wall toward the surface ofan object 1 and toward the outside of the pressure-reduced area 50, themain part 363 which extends from the bellows 362, along the surface ofan object 1 and toward the outside of the pressure-reduced area 50, andthe extension 364 which extends from the main part 363, away from thesurface of an object 1 and toward the outside of the pressure-reducedarea 50.

The suction opening member 36, together with the suction opening 2, thebellows 38, the movable pressure-receiving member 37 and the surface ofan object 1, defines the pressure-reduced area 50.

Pasted onto the area which faces the surface of an object 1 of the mainpart 363 of the suction opening member 36 is a sheet-shapedgroove-forming member 37 made of a material with a low coefficient offriction, such as ultrahigh molecular polyethylene, as is the case withthe device shown in FIG. 1 through FIG. 16. Detailed descriptions of thegroove-forming member 34 are omitted as they are the same as those ofthe device shown in FIG. 1 through FIG. 16.

In FIG. 19, the second pressure-reduced area 383 is in communicationwith the IN port of a 3-port 2-position solenoid valve via hose 385. TheOUT port of the solenoid valve is in communication with the suctioninlet of a vacuum pump. The EX port of the solenoid valve is incommunication with the outside of the pressure-reduced area 50.

In communication with the pressure-reduced area 50 is a vacuum switchwhich will be turned on if and when the negative pressure of thepressure-reduced area 50 increases and exceeds a predetermined value,and, by the action of the vacuum valve, the solenoid of the solenoidvalve is not exited when the negative pressure of the pressure-reducedarea 50 is below the predetermined value and is excited when thenegative pressure of the pressure-reduced area 50 exceeds thepredetermined value.

In FIG. 20, the vertical axis shows the degree of vacuum of thepressure-reduced area 50 and the second pressure-reduced area 383, andthe horizontal axis shows the passage of time. The curve a shows thedegree of vacuum of the pressure-reduced area 50, and the curve b showsthe degree of vacuum of the second pressure-reduced area 383. The thickline SV shows the state of excitement of the solenoid of the solenoidvalve, and the thick line BR shows the state of detachment, from thesurface of an object 1, of the area of the main part 363 of the suctionopening member 36 closest to the inside of the pressure-reduced area 50.

Actions and effects of the device described above will be explainedbelow referring to the FIG. 17 through FIG. 20.

When the electric motors with reduction gears 24L, 24LL, 24R and 24RRare operated to rotate and drive the driving wheels 22 d, 22 c, 22 b and22 a in the same direction, the device will move straight (forward orbackward) along the surface of an object 1. When the driving wheels 22 dand 22 c, on one hand, and the driving wheels 22 b and 22 a, on theother hand, are rotated and driven to opposite directions, the devicewill turn (left or right).

When the negative pressure forming means (not illustrated) is energized,the fluid, such as air, inside the pressure-reduced area 50 becomesdischarged externally through the connecting pipe 10 a and suction hose(not illustrated), resulting in the desired reduction of the pressure ofthe pressure-reduced area 50.

When the pressure is so reduced of the pressure-reduced area 50, thepressure of the ambient fluid, such as air, which acts on the suctionhousing 2 due to the fluid pressure difference between the inside andthe outside of the pressure-reduced area 50, is transmitted to thesurface of an object 1 via the two sets of installation members 12 forthe electric motors with reduction gears, the four sets of electricmotors with reduction gears 24R, 24L, 24RR and 24LL and the four sets ofdriving wheels 22 a, 22 c, 22 b and 22 d, causing the device tosuction-adhere to the surface of an object 1 due to the pressure of theambient fluid.

While the pressure of the inside of the pressure-reduced area 50 ismaintained at a desired level, the main part 363 of the suction openingmember 36 is forced to be in firm contact with the surface of an object1 by the pressure of the outside of the pressure-reduced area 50,thereby stopping as much as possible the fluid outside thepressure-reduced area 50 from flowing internally.

Many grooves are formed in the area of the main part 363 which faces thesurface of an object 1. More specifically, the groove 371 whichcommunicates with the outside of the pressure-reduced area 50 and thegroove 372 which communicates with the inside of the pressure-reducedarea 50 are formed alternately. The groove 372 is constantly in thestate of negative pressure, and therefore, the main part 363 isnecessarily pushed against the surface of an object 1 by the pressure ofthe fluid outside the pressure-reduced area 50.

When the second pressure-reduced area 383 is in communication with theoutside of the pressure-reduced area 50, the movable pressure-receivingmember 37 does not receive the force of being moved away from thesurface of an object 1 nor does it receive the force of being movedcloser to the surface of an object 1, and stays in the state ofneutrality.

When the negative pressure of the inside of the pressure-reduced area 50increases and exceeds a predetermined level, the contact point of thevacuum switch is turned on, exciting the solenoid of the solenoid valve,allowing the second pressure-reduced area 383 to be in communicationwith the vacuum pump (at those points in time t1, t11 and t 21 in FIG.20).

The movable pressure-receiving member 37 is then forced to move awayfrom the surface of an object 1 by the pressure of the fluid outside thepressure-reduced area 50.

The movable pressure-receiving member 37 then pulls the bellows 362 ofthe suction opening member 37 away from the surface of an object 1,finally resulting in the area of the main part 363 of the suctionopening member 36 closest to the inside of the pressure-reduced area 50being detached from the surface of an object 1 (at those points in timet2, t12 and t22 in FIG. 20).

The fluid outside the pressure-reduced area 50 is now caused to flowinside the pressure-reduced area 50 via the groove 371, stopping thenegative pressure of the inside of the pressure-reduced area 50 fromincreasing. When the pressure of the inside of the pressure-reduced area50 returns to the desired level, the contact point of the vacuum switchis turned off, stopping the excitement of the solenoid of the solenoidvalve, thereby allowing the second pressure-reduced area 383 to be incommunication with the outside of the pressure-reduced area 50 again (atthose points in time t3, t13 and t23 in FIG. 20).

By the actions of the restoring force of the two sets of bellows 38which attempt to return to the original shape and the pulling force ofthe suction opening member 36 which receives the pushing force towardthe surface of an object 1, the movable pressure-receiving member 36then moves toward the surface of an object 1, returning to the samestate as when the pressure of the inside of the pressure-reduced area 50was maintained at the desired level (at those points in time t4 and t14in FIG. 20).

The above-described mode of the second most preferred embodiment issomewhat different from that of the most preferred embodiment, but theformer achieves similar effects to those of the latter.

Preferred embodiments of the device of the present invention weredescribed above. In addition to the preferred embodiments, there may bevarious other embodiments of the device of the present invention withinthe scope of the claims made herein.

For example, according to the preferred embodiments described above, themain part of the suction opening member is detached from the surface ofan object by the action of the pressure outside the pressure-reducedarea due to the fluid pressure difference between the inside and theoutside of the pressure-reduced area, i.e., by the action of thepressure which causes it to move away from the surface of an object, butsuch detachment from the surface of an object may be caused by theaction of an actuator, such as a pneumatic cylinder.

Further according to the preferred embodiments described above, the mainpart of the suction opening member has a sheet-shaped groove-formingmember pasted on the area which faces the surface of an object, but thesuction opening member and the groove-forming member may be formed inone piece.

Further according to the preferred embodiments described above, thesuction opening member and the movable pressure-receiving member areseparate members, but they may be formed in one piece.

Further according to the preferred embodiments described above, asheet-shaped groove-forming member is pasted onto the area, which facesthe surface of an object, of the main part of the suction openingmember, but the area which faces the surface of an object of the mainpart of the suction opening member may not necessarily have groovesformed thereon.

Further according to the preferred embodiments described above, a partof the main part of the suction opening member is detached from thesurface of an object, but the device may be so configured that theentire main part is detached.

Further according to the preferred embodiments described above, thesuction opening member is of an approximate ring shape of a ring andcomprises the flanges, the bellows consisting of the upper wall whichextends from the flanges toward the surface of an object and toward theinside of the pressure-reduced area and the lower wall which extendsfrom said upper wall toward the surface of an object and toward theoutside of the pressure-reduced area, the main part which extends fromthe bellows, along the surface of an object and toward the outside ofthe pressure-reduced area, and the extension which extends from the mainpart away from the surface of an object and toward the outside of thepressure-reduced area, but, depending upon the purpose of the use of thedevice of the present invention, a simple cylindrical shape will beacceptable. Further, depending upon the purpose of the use of the deviceof the present invention, the suction opening member may be made of arigid material instead of a flexible material.

The descriptions above of the preferred embodiments of the device of thepresent invention assumed that the device of the present inventionexisted on the surface of an object in the atmosphere, but the device ofthe present invention may be applied underwater. In such a case, a waterpump or a water-driven ejector, instead of a vacuum pump, may be used asa negative pressure forming means.

The device of the present invention is capable of effectively sucking inand transporting materials which exist on the surface of an object,whether existing inside or outside the pressure-reduced area because,according to the device of the present invention, the entire flow of thefluid which flows from outside the suction device, through the inside ofthe suction device and to the negative pressure forming means passesextremely close to the surface of an object.

The device of the present invention is capable of effectively sucking inand transporting materials because, according to the device of thepresent invention, the suction opening member is detached from thesurface of an object, i.e., the surface of a material to be sucked inand transported, due to the increase in the negative pressure of theinside of the suction nozzle, i.e., a suction device, stopping excessiveflow of such material into the suction opening member before suchmaterial is blocked up in the midst of its transportation route.

The device of the present invention is capable of effectively sucking inand transporting materials because, according to the device of thepresent invention, the entire flow of the fluid which flows from outsidethe suction device, through the inside of the suction device and to thenegative pressure forming means passes extremely close to the materialto be sucked in and transported.

When the fluid suction capacity of a negative pressure forming means isconsiderably great, the device of the present invention is capable ofeasily stopping the increase in the negative pressure of thepressure-reduced area without using a large vacuum breaker as hastraditionally been the case. The device of the present invention may bemade smaller and lighter with reduced manufacturing cost, compared totraditional devices which use large vacuum breakers.

POTENTIAL INDUSTRIAL APPLICATIONS

The suction device having a negative pressure adjusting mechanism asdescribed above may be conveniently used as a suction device of a devicewhich utilizes negative pressure and works on the surface of an objectfor various purposes. Further, this invention may be applied to such adevice capable of adhering to the surface of an object, such as a wallsurface or a ceiling surface, by utilizing negative pressure and ofmoving along such surface as is disclosed in U.S. Pat. No. 1,323,843,and may be conveniently used as a device which conducts peeling work ofold painted film off, and painting work on, the surface of largestructures, such as ships' hulls, various tanks and buildings, as wellas underwater cleaning work of ships' bottoms.

1. A suction device comprising: a suction housing connected to anegative pressure forming means to suck in a fluid; a suction openingmember installed on said suction housing, a part of which is caused tocontact the surface of an object, and which defines a pressure-reducedarea together with said suction housing and said surface of an object;and, a means for maintaining the distance between said suction housingand said surface of an object at a predetermined distance; said suctiondevice having a negative pressure adjusting means whereby said suctionopening member and said surface where in contact with each other becomedetached from each other partially or entirely due to the increase inthe fluid pressure difference between the inside and the outside of saidpressure-reduced area, resulting in the communication between the insideand the outside of said pressure-reduced area, allowing the outsidefluid to flow into said pressure-reduced area.
 2. The device of claim 1,wherein: such detachment caused by the increase in the fluid pressuredifference between the inside and the outside of said pressure-reducedarea is then cancelled due to the cancellation of the increase in thefluid pressure difference between the inside and the outside of saidpressure-reduced area, canceling the communication between the insideand the outside of said pressure-reduced area, thereby stopping theoutside fluid from flowing into said pressure-reduced area.
 3. Thedevice of claim 2, wherein: the opening, through which the inside andthe outside of said pressure-reduced area are in communication with eachother, is caused to increase as the fluid pressure difference betweenthe inside and the outside of said pressure-reduced area increases, andis caused to decrease as the increase in said fluid pressure differenceis cancelled.
 4. The device of claim 3, further comprising: a means forcausing said suction opening member and said surface of an object wherein contact with each other to detach from each other partially orentirely due to the increase in the fluid pressure difference betweenthe inside and the outside of said pressure-reduced area.
 5. The deviceof claim 4, further comprising: a means for causing such area ofdetachment between said suction opening member and said surface of anobject to return to the original contacted state due to the cancellationof the increase in the fluid pressure difference between the inside andoutside of said pressure-reduced area.
 6. The device of claim 5, furthercomprising: a means for causing said suction opening member to move awayfrom said surface of an object due to the increase in the fluid pressuredifference between the inside and the outside of said pressure reducedarea.
 7. The device of claim 6, further comprising: a means for causingsaid suction opening member to move toward said surface of an object dueto the cancellation of the increase in the fluid pressure differencebetween the inside and the outside of said pressure-reduced area.
 8. Thedevice of claim 7, wherein: said suction opening member is mounted ontoa movable pressure-receiving member which receives the force of beingmoved away from said surface of an object due to the fluid pressuredifference.
 9. The device of claim 8, wherein: said movablepressure-receiving member is a movable pressure-receiving membercapable, at a predetermined time, of receiving the force of being movedtoward said surface of an object due to the fluid pressure difference.10. The device of claim 9, further comprising: a means for maintainingairtight connection between said movable pressure-receiving means andsaid suction housing while relative positions of said movablepressure-receiving member and said suction housing may change.
 11. Thedevice of claim 10, further comprising: a means for adjusting the forcewhich moves said movable pressure-receiving member away from or towardsaid surface of an object.
 12. The device of claim 11, furthercomprising: a means for causing said movable pressure-receiving memberto move toward said surface of an object due to the cancellation of theincrease in the fluid pressure difference between the inside and theoutside of said pressure-reduced area.
 13. The device of claim 12,wherein: said suction opening member at least comprises a part which isconnected to the suction housing directly or indirectly via anothermember, a part which extends from such connected part toward saidsurface of an object and the part which contacts said surface of anobject, said suction opening member being made of a flexible material.14. The device of claim 13, wherein: grooves which communicate with theoutside of said pressure-reduced area are formed at the part of saidsuction opening member which contacts said surface of an object, saidgrooves causing the inside and the outside of said pressure-reduced areato communicate with each other due to the increase in the fluid pressuredifference between the inside and the outside of said pressure-reducedarea.
 15. The device of claim 13, wherein: grooves which communicatewith the outside of said pressure-reduced area and grooves whichcommunicate with the inside of said pressure-reduced area are formed atthe part of said suction opening member which contacts said surface ofan object, such grooves which communicate with the outside of saidpressure-reduced area causing the inside and the outside of saidpressure-reduced area to communicate with each other due to the increasein the fluid pressure difference between the inside and the outside ofsaid pressure-reduced area.
 16. The device of claim 15, wherein: thesize of the passage of the grooves which communicate with the outside ofsaid pressure-reduced area is caused to increase as the fluid pressuredifference between the inside and the outside of said pressure-reducedarea increases, and the size of said passage is caused to decrease assuch increase in the fluid pressure difference is cancelled.
 17. Thedevice of claim 16, wherein: at least two different lengths of grooveswhich communicate with the outside of said pressure-reduced area areformed.
 18. The device of claim 17, wherein: one or more sheet-shapedgroove-forming member or members having one or more grooves is or arepasted onto the part of said suction opening member which contacts saidsurface of an object for the purpose of forming such groove or groovesthereon.
 19. The device of claim 18, wherein: said suction device has amoving means to move along said surface of an object.
 20. The device ofclaim 19, wherein: the means for maintaining the distance between saidsuction housing and said surface of an object at a predetermineddistance simultaneously serving as the means for moving along saidsurface of an object.